1. Field of the Invention
This invention relates to a focus detecting apparatus for a camera or the like.
2. Related Background Art
There is known a focus detecting apparatus for a camera which is provided with a narrow focus detection area of e.g. about 3 mm in the center of a photographing image field. The focus detecting apparatus of this kind suffers from the following disadvantages.
First, when an object to be photographed by a photographer is at any other location than the center of the photographing image field, the photographer must catch that object in the central focus detection area by changing the direction of the camera and effect focus detection. This leads to bad operability. Second, since the focus detection area is narrow, the object to be photographed will come out of the focus detection area if the photographer slightly changes the direction of the camera.
In order to overcome the above first disadvantage, there has been proposed a focus detecting apparatus in which a plurality of focus detection areas are also provided at other locations than the center of the photographing image field. A camera then automatically selects a focus detection area by a predetermined algorithm to thereby effect focus detection. In such a focus detecting apparatus, however, an area which is not the object of focus by the photographer may be selected and the focus detection of the object in that area may be effected in some cases.
There has also been proposed a focus detecting apparatus designed such that from among a plurality of focus detection areas disposed at intervals in the photographing image field, the photographer manually selects an area to thereby effect focus detection. However even such a focus detecting apparatus cannot overcome the above-noted second disadvantage.
Further, if the number of focus detection areas is increased, an object can be caught in a wide range in the image field, while there is the disadvantage that focus detection time becomes long.